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Background Water hyacinth (Eichhorniacrassipes) is one of the most uncompromising weeds in the whole world. Its adverse effects due to fast growth rate are main physical interference with fishing and navigation. Water hyacinth also causes eutrophication due to the large release of organic nutrients after its degradation, consequentially deterioration of water quality and also adversely affecting aquatic flora and fauna. Therefore, composting is one of the best methods for control and utilization of water hyacinth. Water hyacinth being the plant material is rich in cellulose, hemicellulose, and lignin content which hinders the rate of degradation during composting. The raw materials including water hyacinth along with sawdust and cattle manure in five different proportions trial 1 (10:0:0), trial 2 (8:1:1), trial 3 (7:2:1), trial 4 (6:3:1), and trial 5 (5:4:1) were composted using rotary drum composter. Results Final product of water hyacinth composting was flourishing of nutrients such as nitrogen, phosphorus, sodium, potassium, calcium, and magnesium. The lignin reduction in all the five trials was obtained between 10 and 40 %. The reduction in cellulose was observed ranging from 4 to 55 % in different trials. Similar as cellulose and lignin, hemicellulose was also reduced about 11-46 % in all five trials during the process. Conclusion The maximum reduction inorganic matter, lignin, cellulose and hemicellulose was observed in trial 4;whereas, the nutrient contents (nitrogen, phosphorus, Na, K, Ca, and Mg) were increased significantly during the process. On analyzing the FTIR results, trial 4 showed that aliphatic and polysaccharides have easily degraded and aromatic compounds have increased with composting time in trial 4.

The presence of heavy metals in the environment due to industrial activities is of serious concern because of their toxic behaviour towards humans and other forms of life. Biosorption of Pb(II) using dry bacterial biomass of Bacillus badius AK, previously isolated from water hyacinth compost, has been undertaken in batch system. The optimum conditions of biosorption were determined by investigating the initial pH, contact time, initial biomass dosage at constant temperature of 40 °C, initial metal concentration of 100 mg/L and rotational speed of 150 rpm. The optimum pH was found to be 5 and equilibrium contact time was 2.5 h. The maximum biosorption capacity of Pb(II) on Bacillus badius AK was 138.8 mg/g at an initial concentration of 100 mg/L. A kinetics study revealed that the adsorption process followed pseudo second order rate kinetics. The experimental data were fitted to the Langmuir isotherm. Characterization of the biomass indicated the presence of several functional groups. The results indicated that the bacterium Bacillus badius AK is efficient for the removal of Pb(II).

Water hyacinth is a noxious aquatic weed growing over a wide variety of wetland. One of the effective methods of its treatment is rotary drum composting. Hence, microbial succession in the rotary drum composting of water hyacinth was studied along with stability and maturity. Different ratios of water hyacinth, cow dung and sawdust, i.e. 8 : 1 : 1, 7 : 2 : 1, 6 : 3 : 1, 5 : 4 : 1 and 10 : 0 : 0 (control), respectively, were taken. A total weight of 150 kg was maintained. Maximum degradation was observed in the trial 3 (6 : 3 : 1), which showed maximum temperature rise up to 56.5• C. The total mesophilic bacterial count changed from 4.73 × 10 12 to 2.5 × 10 7 colony forming unit (CFU)/g compost during the composting period. Spore forming population reached the highest count of 3.3 × 10 10 CFU/g in the thermophilic phase of composting. Actinomycetes, streptomycetes and fungi counts decreased to about 2.4 × 10 7 CFU/g, 6.5×10 5 CFU/g and 6.79 × 10 5 CFU/g, respectively, at the end of composting period. A maximum reduction of 78.7% in oxygen uptake rate and 90.6% in CO2 evolution rate was observed. This showed the highest stability of the compost sample. But the maximum volatile solids reduction of 45.9% signified the high content of recalcitrant lignocellulosic material. Indicator organisms were reduced to acceptable standards of sanitation.

Purpose The present work aims to isolate and identify bacterial community from the rotary drum compost of green waste such as the water hyacinth. Compost quality was also investigated with the physicochemical parameters and the heavy metal analysis. Methods For rotary drum composting, a waste mixture of 150 kg with water hyacinth, cow dung and sawdust were prepared in the proportion of 6:3:1, respectively. The physicochemical parameters such as pH, temperature, volatile solids and the electrical conductivity were analyzed to detect the compost quality. Pb, Ni, Zn, and Cd were investigated for total heavy metals, toxicity characteristic leaching procedure (TCLP), diethylenetriaminepentaacetic acid (DTPA) and water solubility tests. Consistent and active bacterial community were isolated from the rotary drum compost of water hyacinth. Culturedependent and culture-independent techniques were approached for the isolation process.Results Twelve bacteria were isolated and identified by 16S rDNA sequencing and phylogenetic analysis; they majorly belonged to the Bacillus and Enterobacter family. The analysis of temperature, pH, EC, VS and heavy metals depicted the good quality of compost. Heavy metals concentration was in Pb [ Ni [ Zn [ Cd; however, for Pb, Cd and Ni water solubility remained non-detectable, DTPA concentration for Pb and Cd was also found to be nondetectable. Conclusions The microbes in water hyacinth compost are metabolically active degrading the organic matter, surviving in the heavy metal-loaded compost environment. Thus, green waste (water hyacinth) can be utilized to isolate bacterial species in anticipation of their application in heavy metal removal in liquid and solid waste sources for micro-bioremediation.